TheAfricanelephantthelargestlandanimalremainingontheearthisofgreatimportancetoAfricanecosystem(生态系统).UnlikeotheranimalstheAfricanelephantistoagreatextentthebuilderofitsenvironment.Asabigplant-eateritlargelyshapestheforest-and-savanna(大草原)surroundingsinwhichitlivesthereforesettingthetermsofexistenceformillionsofotheranimalsthatliveinitshabitat.

Itistheelephant’sgreatdesireforfoodthatmakesitadisturberoftheenvironmentandanimportantbuilderofitshabitat.Initscontinuoussearchforthe300poundsofplantsitmusthaveeverydayitkillssmalltreesandunderbushesandpullsbranchesoffbigtrees.ThisresultsinnumerousopenspacesinbothdeeptropicalforestsandinthewoodlandsthatcoverpartoftheAfricansavannas(热带草原).Intheseopenspacesarenumerousplantsinvariousstagesofgrowththatattractavarietyofotherplant-eaters.

Taketherainforestsforexample.Intheirnaturalstatethespreadingbranchesoverheadshutoutsunlightandpreventthegrowthofplantsontheforestfloor.Bypullingdowntreesandeatingplantselephantsmakeopenspacesallowingnewplantstogrowontheforestfloor.Insuchsituationstheforestsbecomesuitableforlargehoofedplant-eaterstomovearoundandforsmallplant-eaterstogettheirfoodaswell.

WhatworriesscientistsnowisthattheAfricanelephanthasbecomeanendangeredspecies.Iftheelephantdisappearsscientistssaymanyotheranimalswillalsodisappearfromvastareasofforestandsavannagreatlychangingandworseningthewholeecosystem.

【小题1】Whatisthepassagemainlyabout?

A．DisappearanceofAfricanelephants.B．ForestsandsavannasashabitatsforAfricanelephants.C．TheeffectofAfricanelephants’searchforfood.D．TheeatinghabitofAfricanelephants.【小题2】Whatdoestheunderlinedphrase“settingtheterms”mostprobablymean?A．Fixingthetime.B．Worseningthestate.C．Improvingthequality.D．Decidingtheconditions.【小题3】AccordingtothepassagewhichofthefollowingstatementsisTRUE?